Method and composition

ABSTRACT

A method of dispersing an insoluble material in an aqueous solution comprising the following steps: 
     (i) providing a formulation comprising at least one insoluble material and at least one dispersant comprising a water soluble agriculturally acceptable derivative of an alternating copolymer or an agriculturally acceptable salt thereof wherein said alternating copolymer comprises at least one first comonomer residue according to formula I and at least one second comonomer residue according to formula II; and                    
     (ii) dispersing said formulation in an aqueous medium. 
     An agricultural formulation comprising at least one insoluble material and at least one dispersant comprising a water soluble agriculturally acceptable derivative of an alternating copolymer or an agriculturally acceptable salt thereof wherein said alternating copolymer comprises at least one first comonomer residue according to formula I and at least one second comonomer residue according to formula II.

The present invention relates generally to dispersants, for use inagricultural applications, in particular the present invention relatesto methods for the dispersion of insoluble material with copolymericdispersants which dispersions are formed with improved dispersibilityand show improved suspensibility. The present invention also relates tomethods of producing dispersible formulations, the formulations per seand methods of treating substrates with dispersions produced from suchformulations.

The active principles in many agricultural applications are largelyhydrophobic or water insoluble in character and are, by necessity, oftenadministered as finely divided solids suspended in aqueous media. Themajority of these active principles are manufactured and marketed inconcentrated form, possibly with the addition of other insoluble inertfillers, which are then diluted prior to application. For example, theactive principle is typically available in the form of a suspensionconcentrate (SC), wettable powder (WP) or water dispersible granule(WG). However, due to the generally hydrophobic nature of the activeprinciple, the addition of a suitable dispersant is essential in orderto achieve an homogenous dispersion with a minimum of mixing, such asmay be achieved readily by hand or with minimal mechanical mixing.Furthermore, once an homogenous dispersion is achieved, the resultingsuspension must remain stable for a time sufficient, at least, to allowapplication by usual means such as spraying. Any settling, agglomerationor flocculation of the finely divided solid may lead to inconsistent andineffective application as well as blockage of the spraying equipment.It is therefore necessary to provide a dispersant which provides easyand homogenous dispersion and results in a suspension which maintainsits stability during the application of the aqueous dispersion.

Effective dispersants for use in these applications ideally provide asuspension with acceptable dispersibility, suspensibility and lack ofagglomeration. The Collaborative International Pesticides AnalyticalCouncil (CIPAC Handbook Volume 1) defines methods that can be used fordetermining acceptable suspensibility (MT 15.1) and degree ofagglomeration (MT 59.3). For example, in suspension concentratesso-called SC formulations, this can be achieved by the addition of about3-5 w/w % of a standard dispersant. Wettable powder (WP) and waterdispersible granule (WG) formulations generally require the addition ofstandard dispersant in the order of 6-7 w/w % in order to achieveacceptable suspensibility and degree of agglomeration as determined by awet sieve retention test. (MT 59.3).

Currently used dispersants for SC formulations include ethyleneoxide/propylene oxide block copolymer surfactants based on anhydrophobic moiety plus ethyleneoxide. Also used are ether phosphatederivatives of non-ionic surfactants, especially of tristyrylphenolethoxylates. Conventional anionic surfactants used include sulphonatedderivatives of arylformaldehyde condensates, polyacrylates andlignosulfonates.

Dispersants for WP and WG formulations are usually limited by therequirement that the dispersant be solid at ambient temperatures, benon-gelling and not dissolve the active principle. For these reasons,conventional non-ionic surfactants are often unsuitable, and anionicdispersants are preferred. Known effective dispersants for WP and WGformulations include sulphonated alkylnaphthalene/formaldehydecondensate salts and lignosulfonate salts.

α-Olefin-polycarboxylate copolymers are well known as dispersants in awide range of applications including pigment dispersion, emulsionpolymerisation, cosmetics and pesticidal compositions. As far back as1972 the sodium salt of a maleic anhydride and diisobutylene copolymerwas given an exemption from tolerance for use in pesticide formulationsby the United States Environmental Protection Authority following apetition from Rohm and Haas Co. FR 2545325 describes the use of ammoniumand alkali metal salts of maleic anhydride-diisobutylene copolymer inpesticide granules. Similarly, EP 201417 describes the use of copolymersof maleic anhydride with surfactants selected from sulfates andphosphates of ethoxylated phenol derivatives in WP and WG formulations.JP 62036302 describes copolymers having a molecular weight range of from5000-20000 for use with granular agrochemical compositions. Maleicanhydride and diisobutylene copolymer derivatives are described for usein conjunction with CaCO₃ and Mg salts for SC formulations in JP 0609,302. The use of sulfonated derivatives of copolymers of maleicanhydride in water dispersable granules is also described in JP58-131903.

French Patent No. 2,397,444 describes stable and concentrateddispersions of active materials which may be prepared from non-dustingpowders or granular materials. It is necessary to separate the activematerial in the presence of a salt of an acidic resin, such as, forexample, a copolymer of maleic anhydride and an α-olefinic compound; addan organic solvent which forms, together with the aqueous medium, atwo-phase system; treat such two-phase system by adding a carriersubstance thereto; and then isolate the product by a reduction in thevolume of the organic phase by the addition of water, the solventgradually transferring into the added water.

We have now found that the use of derivatives of an alternatingcopolymer of α-methyl styrene and maleic anhydride provides surprisinglyimproved dispersibilty and suspensibility in agrochemical formulations,as well as a number of other ancillary benefits which will be more fullydescribed herein.

According to a first aspect of the present invention, there is provideda method of dispersing an insoluble material in an aqueous solutioncomprising the following steps:

(i) providing a formulation comprising at least one insoluble materialand at least one dispersant comprising a water soluble agriculturallyacceptable derivative of an alternating copolymer or an agriculturallyacceptable salt thereof wherein said alternating copolymer comprises atleast one first comonomer residue according to formula I and at leastone second comonomer residue according to formula II; and

(ii) dispersing said formulation in an aqueous medium.

According to a second aspect of the present invention, there is provideda method of making an agrochemical formulation comprising the steps of:

(i) combining at least one insoluble material, and at least onedispersant comprising a water soluble agriculturally acceptablederivative of an alternating copolymer or an agriculturally acceptablesalt thereof wherein said alternating copolymer comprises at least onefirst comonomer residue according to formula I and at least one secondcomonomer residue according to formula II in an aqueous medium;

(ii) milling said combination to a particle size range in order toobtain a stable, readily-suspendible aqueous dispersion; and

(iii) stabilising said aqueous dispersion to obtain an SC formulationsuitable for dilution in water for agricultural use.

According to a third aspect of the present invention, there is provideda method of making an agrochemical formulation comprising the steps of:

(i) combining at least one insoluble material, with at least onedispersant comprising a water soluble agriculturally acceptablederivative of an alternating copolymer or an agriculturally acceptablesalt thereof wherein said alternating copolymer comprises at least onefirst comonomer residue according to formula I and at least one secondcomonomer residue according to formula II; and

(ii) milling said combination to a desired particle size to obtain ahomogeneous wettable powder (WP) formulation.

According to a fourth aspect of the present invention, there is provideda method of making an agrochemical formulation comprising the steps of:

(i) combining at least one insoluble material suitable for agriculturaluse with at least one dispersant comprising a water solubleagriculturally acceptable derivative of an alternating copolymer or anagriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII; and

(ii) blending said combination to obtain a homogeneous wettable powder(WP) formulation.

According to a fifth aspect of the present invention, there is provideda method of making an agrochemical formulation comprising the steps of:

(i) combining at least one insoluble material suitable for agriculturaluse with at least one dispersant comprising a water solubleagriculturally acceptable derivative of an alternating copolymer or anagriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII;

(ii) agglomerating said combination to form discrete granular materials;and

(iii) drying said granular materials to obtain a water dispersiblegranule WG formulation.

According to a sixth aspect of the present invention, there is provideda formulation produced by the process of the second, third, fourth andfifth aspects.

According to a seventh aspect of the present invention, there isprovided an agricultural formulation comprising at least one insolublematerial and at least one dispersant comprising a water solubleagriculturally acceptable derivative of an alternating copolymer or anagriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII.

According to an eighth aspect of the present invention, there isprovided a method of treatment of a substrate with a insoluble materialcomprising the following steps:

(i) preparing a formulation comprising at least one insoluble materialand at least one dispersant comprising a water soluble agriculturallyacceptable derivative of an alternating copolymer or an agriculturallyacceptable salt thereof wherein said alternating copolymer comprises atleast one first comonomer residue according to formula I and at leastone second comonomer residue according to formula II;

(ii) dispersing said formulation in an aqueous medium; and

(iii) applying the dispersed formulation to a substrate.

The dispersants for use in the present invention are based onalternating copolymers. It will be understood by those skilled in theart that alternating copolymers may be prepared by the careful selectionof comonomers and reaction conditions. As is well known in the art,often additional polymerization conditions should be observed in orderto obtain an alternating copolymer. For example the temperature and typeof solvent can influence whether an alternating or other type ofcopolymer is formed. Methods for making such alternating copolymershaving first and second comonomer residues according to formulae I andII respectively will be well known to those skilled in the art ofpolymer synthesis.

The alternating, or substantially alternating character, of thecopolymers is believed to be of importance to the present invention. Theperson skilled in the art will understand the degree of regularitynecessary in order for a copolymer to be considered of alternatingcharacter. It is preferred that the alternating copolymer has analternating character defined by greater than 70% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer, more preferably greater than 90%. Ahigh degree of control in the synthesis of such copolymers is requiredin most cases to achieve this.

The alternating copolymer may contain additional comonomer residues. Forexample, the addition of a small amount, say less than 10%, of methylmethacrylate will not substantially change the alternating character ofthe copolymer. Suitable alternating copolymers for use in the presentinvention also include copolymers of three or more comonomers. While notwishing to be bound by theory it appears that where a consistenthydrophobic polymer backbone is provided in the presence of regularlyspaced anionic charge along the polymer molecule such as obtained by analternating copolymer, the improved dispersant performance is obtained.

While not wishing to be bound by theory, it is believed that thestiffness of the polymer molecule is related to its performance as adispersant. It is believed that improved dispersant performance isrelated to the degree of steric hindrance and thereby resistance of thecopolymer to free rotation.

The dispersants are agriculturally acceptable salts or water-solubleagriculturally acceptable derivatives of the alternating copolymer andare preferably readily soluble in water. Suitable salts include alkalimetal salts such as the sodium or potassium salt of the alternatingcopolymer. Ammonium salts of the alternating copolymer may be used,however some ammonium salts which contain significant levels ofby-products appear to have some limitations on their use since they havebeen found to be unsuitable in some WG formulations. While not wishingto be bound by theory, it is believed that they appear to disintegrationof the granule and lead to formation of non-dispersing aggregates. Whileagriculturally acceptable salts of the alternating copolymer aregenerally preferred, the alternating copolymer may be provided in theformulation in addition to a source of suitable cations where theaddition of the cation source to aqueous media solubilises thealternating copolymer.

Preferably the amount of suitable cations is sufficient to provideoptimum dispersant characteristics in the alternating copolymer. It isgenerally desirable to provide an excess of cations such that asubstantial amount of the alternating copolymer forms polyanionicpolymer.

The anhydride of the alternating copolymer is not generally soluble inwater. However, we have found that the free acid shows a degree ofsolubility in water. In one embodiment the formulation may contain thefree acid of the alternating copolymer (in the absence of any suitablecation source). A cation source may be provided in a separate additionto the aqueous medium prior to the dispersing of the formulation.

We have found that certain combinations of free acids of the alternatingcopolymer with separate addition of a cation source prior to dispersingthe formulation are advantageous. It is believed that the reactionbetween the free acid and the cation source generates gas and the actionof which facilitates the disintegration of the granule containing theinsoluble material. In particular, the addition of sodium carbonateleads to the generation of carbon dioxide and results in improveddisintegration of the granule. Other cation sources may be selected soas to generate a variety of gaseous reaction products to provideimproved dispersion.

Cation sources suitable for incorporation into either the formulation orthe aqueous medium include sources of agriculturally acceptable cations,such as alkali metal cations. Preferably the cation source is selectedfrom the group consisting of alkaline salts such as carbonates,bicarbonates, hydroxides, phosphates, alkoxides, borates, sulphites andsilicates. Other water soluble agriculturally acceptable derivatives ofthe alternating copolymer include polyethyleneoxy derivatives,polyethyleneglycol derivatives, polyamide derivatives and polyvinylalcohol derivatives. By water-soluble it is meant that the derivativesof the alternating copolymer are at least partially water-soluble atambient temperatures. Other water-soluble derivatives of the alternatingcopolymer are also useful in the present invention.

The preferred molecular weights of the alternating copolymers are in therange of from 1000 to 90000 daltons. We have found that certain highermolecular weight alternating copolymers show a certain degree ofintractability in solution and our more preferred range is from10,000-40,000 daltons.

We have found that agriculturally acceptable salts of alternatingcopolymers as described herein for use as dispersants in agriculturalcompositions provide improved and consistent dispersant performance whencompared to conventionally used dispersants such as sulphonatedalkylnaphthalene formaldehyde condensate salts.

It is surprising that agriculturally acceptable salts of alternatingcopolymers as described herein give enhanced performance when comparedto previously described preferred structures in the prior art such asfor example diisobutylene isobutylene and styrene copolymers with maleicanhydride while still other derivatives described in those samepublications, cannot be reasonably used as dispersants in agriculturalapplications at all. For example we have found that some styrene-maleicanhydride copolymer derivatives resulted in less stable and sometimesunstable dispersion. Similarly some linear α-olefin maleic anhydridederivatives such as those derived from n-octene and n-decene alsoyielded unstable dispersions affording poor suspensibility.

The performance of the agriculturally acceptable salts of alternatingcopolymers described herein can also be compared to diisobutylenederivatives by comparing the suspensibility observed at differentdispersant concentrations in WP and WG formulations. The lower thedispersant concentration at which an acceptable suspensibility resultremains, the more efficient is the surface coverage of the dispersant.In practical terms this means the dispersant will be more cost effectiveto the end user. When the use rate of agriculturally acceptable salts ofalternating copolymers of the present invention is compared to that of adiisobutylene maleic anhydride sodium salt of similar molecular weightwe have found that the agriculturally acceptable salts of alternatingcopolymers of this invention may give acceptable stability at aconcentration significantly lower than the corresponding diisobutylenederivative.

Methods for making such alternating copolymers having first and secondcomonomer residues according to formulae I and II respectively will bewell known to those skilled in the art of polymer synthesis.

The dispersant system used in embodiments of the present invention maybe a mixture of the alternating copolymer as herein described with otherdispersants known to those skilled in the art, including alkylsubstituted and unsubstituted sulfonated naphthalene formaldehydecondensate salts, alkyl substituted and unsubstituted phenolformaldehyde condensate salts, lignosulphonate salts, polyacrylatesalts, and other olefin-unsaturated carboxylic acid copolymerderivatives.

In agrochemical applications, a wide variety of insoluble materials suchas active principals are delivered in aqueous suspension. Activeprincipals such as those used in WP, WG and SC formulations aregenerally insoluble at ambient temperatures. Water insoluble materialswhich may advantageously be used in WP, WG and SC formulations includeherbicides, insecticides, fungicides, biocides, molluscicides,algaicides, plant growth regulators, anthelmintics, rodenticides,nematocides, acaricides, amoebicides, protozoacides, crop safeners andadjuvants. Examples of such actives commonly granulated or made aspowders in agriculture include: triazine herbicides such as simazine,atrazine, terbuthylazine, terbutryn, prometryn and ametryn, ureaherbicides such as diuron and fluometron, sulphonyl urea herbicides suchas chlorsulfuron, metsulfuron methyl, nicosulfuron and triasuifuron,sulphonanilide herbicides such as flumetsulam, organophosphateinsecticides such as azinphos methyl, chlorpyrifos, sulprofos andazamethiphos, carbamate insecticides such as aldicarb, bendiocarb,carbaryl and BPMC, synthetic pyrethroids such as bifenthrin, as well asvarious types of fungicides including dimethomorph, benomyl,carbendazim, mancozeb, triazoles such as hexaconazole and diniconazole,acaricides such as propargite. A list of such products can be drawn fromthe Pesticide Dictionary (contained in the Farm Chemicals Handbook) orthe British Crop Protection Society. Pesticides Manual.

In addition, some fertilizers and also water soluble active principlesmay use water dispersible formulations either by addition of inertcarriers for convenience in handling or to aid in a controlled releaseformulation.

A wide variety of other insoluble materials are used in agriculturalapplications including fillers and carriers, for example but not limitedto, natural and synthetic silicates and silicate minerals, mineraloxides and hydroxides and also natural and synthetically derived organicmaterials. Such materials may be added as porous carriers, as moistureinhibition agents, to aid binding or agglomeration properties of aformulation or simply to fill a formulation to a convenient weight.Examples of such fillers may include natural silicates such asdiatomacious earth, synthetic precipitated silicas, clays such askaolin, attapulgites and bentonites, zeolites, titanium dioxide, ironoxides and hydroxides, aluminium oxides and hydroxides, or organicmaterials such as bagasse, charcoal, or synthetic organic polymers.These other insoluble materials may be readily dispersed in accordancewith the present invention.

An additional agent conventionally used in combination with dispersantsused in the above formulations is a surfactant wetting agent. The roleof the wetting agent in the case of SC formulations is to aid removal ofair from particle surfaces during manufacture and to aid dilution inwater. In the case of WP formulations the role of the wetter may be toaid penetration of the solids into water, while in the case of WGformulations it may aid penetration of the granules into water and aiddisintegration of granules back to primary particle size. In some casesthe dispersant may itself function as a suitable wetting agent while inothers the dispersant may show an antagonistic effect on the wetter. Asa further embodiment of the present invention at least one surfactantwetting agent may be selected from the group consisting of analkylpolysaccharide; di or mono alkyl sulphosuccinate derivative; anonionic surfactant loaded onto an inert silicate carrier; and anon-ionic surfactant delivered in the form of a urea surfactant complex.

The step of dispersing the formulation in an aqueous medium may beachieved by any convenient means dependent on the nature of theformulation. It is desirable that the dispersion of the formulation inan aqueous solution may be conducted either by hand or with a minimum ofmechanical agitation. Mechanical agitation may include stirring, mixing,blending and other similar processes.

The suspension of insoluble material in aqueous medium will be typicallyused for the treatment of a substrate such as plant or otheragricultural medium. The application of the suspension onto thesubstrate may be achieved by any convenient means, including spraying,and the like. Granules are generally dispersed in water prior to beingsprayed by the farmer. Farm sprays may be as a small back-pack handsprayor a large boom spray or other convenient means. Aerial spraying is alsosometimes used.

Formulations of the present invention may also be applied to thesubstrate directly, prior to dispersion. The subsequent application ofrain or other aqueous media is sufficient for the formulation of thesuspension of particulate material.

The present invention is described with reference to WP, WG and SCformulations. In each case, formulations provide a stable aqueousdispersion of finely milled insoluble hydrophobic particles. Thestability properties of the dispersion and hence the effectiveness ofthe dispersion can be measured by means of a suspensibility test asdescribed by the CIPAC test MT 15.1. In this test the volume fraction ofsuspended material is compared to that which has settled out due togravity after 30 minutes. Typically a dispersant achieving a reportedpercentage suspensibility about 80% would be considered as an effectivedispersant for WG and WP formulations, while in excess of 90% would beexpected for an SC formulation. Another measure of the stability of thedispersion is the degree to which particles remain non aggregated. Thismay also be a property of the even distribution of the dispersant in theformulation. The degree to which particles may be aggregated is oftenmeasured by a wet sieve retention test as described in CIPAC test MT59.3. In this test the dispersed solid is poured through a series offine sieves and retained material is measured as a fraction of the totalamount of dispersed material. Formation of such aggregates is a majorproblem observed in WG formulations and to a lesser extent in WPformulations.

Generally WP formulations are produced by milling the active principleeither alone or in combination with fillers, dispersants and/orsurfactant wetters to a suitable average particle size, typically in the5-15 μm range. The milled material is then dry blended with a surfactantwetter, and/or dispersant if not already present or with additionaldispersants and/or surfactant wetters to give a homogeneous composition.The powder formulation is assessed for wettability according to a methodsuch as CIPAC MT 53.5.1 and suspensibility as per CIPAC MT 15.1. Aformulation will desirably have a wettability of less than 1 minute anda suspensibility above 80%. Below 60% would generally be consideredunacceptable. Results which might be commercially acceptable are eitherdetermined by the local registration authority or by the standards setby the formulators themselves.

In the case of WG formulations a suitably milled active ingredient withor without other fillers, typically of average particle size 5 to 15 μmmay be mixed with one or more surfactants wetters and one or moredispersants. Typically an excess of water is added to bind the particlestogether into agglomerates. The excess water is later reduced bysuitable air drying techniques to an optimal level.

The agglomerates are typically granulated using one of many techniquesincluding pan granulation, drum granulation, fluid bed granulation,spray drying, tabletting or extrusion techniques which are well known tothose skilled in the art.

The wetter and dispersant may either be powder blended with the activeingredient or alternatively blended as an aqueous solution in the waterused to aid agglomeration. The active ingredient, fillers, wetter anddispersant may also be milled together in one operation prior to theaddition of water.

For a WG formulation to be acceptable an additional requirement is thatthe said granules should readily disperse in water back to the primarydispersed particle size within a short period. This property is known asdispersibility and in describing the current invention it is measured asthe time taken for granules to disperse back to primary particle size inwater under a standard degree of agitation. A dispersion time of lessthan one minute is desirable, 20 seconds is excellent and 2 minutes ispoor. Desirably the granules should also have good suspensibility.Suspensibility is typically tested using CIPAC MT 15.1. Above 80% is adesirable result, less than 60% is generally regarded as undesirable. Inmany cases when testing granules a so-called maximum surface coverageresult is often obtained. This is where the suspensibility results reacha maximum level then plateau. Adding more dispersant will not generallyimprove the result. This phenomenon is thought to be due to the particlesize distribution of the material. Usually there is a given number ofparticles which are of such a size that they will settle regardless oftype and concentration of dispersant.

Desirably the granules should have low wet sieve retention. Wet sieveretention is typically tested using CIPAC MT 59.3. For the 150 μm sieveless than 0.1% retained material is desirable. Less than 0.02% is moredesirable. Likewise for the 53 μm sieve less than 0.6% is desirable,anything less than this is more desirable.

A further desirable property of a WG formulation is that the granulesshould be non-dusty and resistant to attrition. This is often a propertyof the method of granulation used and the level of compaction thereobtained. Often there is an observed tradeoff between the dispersibilityproperties of a WG formulation and the level of compaction and attritionresistance. Attrition resistance may be measured by subjecting granulesto a set degree of agitation and measuring the level of smallerparticles generated by means of passing through sieves of various sizes,

Storage stability may be tested by storage at 50 degrees celsius andtested as above at I month and 3 month intervals to determine if anyproperties have changed significantly.

Preferably, the granules should maintain these properties on storage.Surprisingly, it has been observed that, upon prolonged storage, solidformulations such as WP and WG formulations containing dispersants suchas those described herein are not as susceptible to deterioration indispersability and suspensibility as formulations of the prior art.Further, it is observed that WG formulations prepared containingdispersants such as those described herein which are prepared bymethods, such as extrusion, leading to a high degree of compaction toafford attrition resistance, will still show ready dispersibility.

We have also found that WP and WG formulations which incorporate thedispersants described herein require typically less dispersant, than forpresently known WP and WG formulations.

As a further embodiment of the present invention in the case of WP andWG formulations the alternating copolymer dispersants herein describedmay be combined with surfactant wetting agents selected from the classescomprising alkylpolysaccharides, dialkyl and monoalkylsulphosuccinatesalts, nonionic surfactants loaded onto porous silicate carriers andurea surfactant complexes of non-ionic surfactants. The wetting agentmay be combined in such formulations at a rate in excess of 1% w/w andpreferably less than 3% w/w. Most preferred from the alkylpolysaccharideclass of wetting agents are alkylpolyglucosides derived from reactionwith glucose and a primary hydrocarbon alcohol. Even more preferred arethe highly crystalline derivatives such as obtained from ECOTERIC AS 20and ECOTERIC AS 10 (Huntsman Corporation Australia Pty Ltd). Mostpreferred from the monoalkylsulphosuccinate class are sodium orpotassium salts of cyclohexyl, iso-octyl and n-octyl sulphosuccinate.Most preferred from the dialkylsulphosuccinate class are sodium orpotassium salts of dicyclohexyl, diisooctyl and di-n-octylsulphosuccinates. Most preferred from the class of nonionic surfactantsloaded onto insoluble porous silicate carriers are ethoxylatedsurfactants loaded onto carriers such as TERIC 157 (Huntsman CorporationAustralia Pty Ltd). Most preferred wetting agents from the ureasurfactant complexes are urea adducts of alcohol ethoxylate surfactantssuch as TERWET 7050 (Huntsman Corporation Australia Pty Ltd). Thewetters herein described show good wettability and dispersibility forthe formulations and have the additional advantage of showing storagestability in combination with the copolymer dispersants described.Whereas by comparison some commonly used WG and WP wetters such asalkylnaphthalene sulphonate salts and lignosulphonate salts have beenfound to show poor storage stability.

In the case of SC formulations in the present invention an activeingredient is typically added to water containing a dispersant,preferably with a surfactant wetting agent together with a conventionalnon-ionic dispersant. A humectant may also be included. A dispersion isformed using high shear mixing. The dispersion is then rnilled by anyone of several means of wet milling so that the mean particle size ofthe dispersed solid is below 5 μm more typically in the range of from 1to 3 μm. The resulting product is known as a millbase and may bemodified with additives such as antifreeze, thickeners and antisettlingagents, biocides and colouring agents may be added. For an SCformulation to be acceptable it should not show a high degree ofthickening, settling or growth of aggregates over time. These physicalproperties can be assessed by visual observation.

SC's generally require good viscosity and storage stability. Storagestability is usually assessed as degree of top settling or syneresis,sedimenting or “claying” which is the tendency to form a sticky layer onthe bottom and “bleeding” which is the tendency of the dispersion toseparate without necessarily displaying even settling. Redispersibilityis also important. These may also be assessed visually.

For SC formulations in the case of dispersants described herein onlycertain dispersant copolymers are suitable. When used alone, somedispersant copolymer derivatives give a viscosity of slurry premixunsuitable for milling so it is preferable to combine the dispersantwith another fast acting well known dispersant such as an EO/PO blockco-polymer type dispersant. While not wishing to be bound by theory itappears that the dispersant needs time to migrate to the surface of thedispersed particles. The dispersant copolymers are used synergisticallywith other known dispersants in some cases.

While the present invention has been described with reference toagrochemnical formulations, it will be apparent that the improvements indispersibility and suspensibility will render the present inventionuseful in other applications. The present invention will now be furtherdescribed with reference to the following non-limiting examples andfigures. All percentages recited herein are by weight of the totalcomposition unless otherwise specified.

EXAMPLE 1

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 3.1 Kaolin 3.1 Water 0.5%

The dispersant used was the sodium salt of an alternating copolymer ofalphamethylstyrene and maleic anhydride of approximate molecular weight30,000 to 40,000.

The granules were prepared by blending the solids with sufficient weightof water such as to give a plastic premix which was then extruded usinga Fuji-Paudal laboratory scale extrusion granulator. The resultinggranules were then dried by means of a fluid bed drier back to a watercontent of approximately 0.5% w/w.

The resulting WG was tested for dispersibility by recording the time inseconds required for total disintegration under uniform agitation. Thesuspensibility was tested according to CIPAC MT 15.1 and the wet sieveretention was tested using 150 μm and 53 μm sieves according to CIPAC MT59.3. The granules were then placed on storage at 50 degrees celsius fora period of 3 months and the above described tests were repeated after 1month and 3 months of storage. Results are recorded in TABLE 1.

EXAMPLE 2

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of a non-alternating 10:3(mole ratio) alphamethylstyrene:maleic anhydride copolymer ofapproximate molecular weight 30,000 to 40,000. Results are shown inTABLE 1.

EXAMPLE 3

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of a non-alternating 4:3 (moleratio) alphamethylstyrene:maleic anhydride copolymer of approximatemolecular weight 30,000-40,000. Results are shown in TABLE 1.

EXAMPLE 4

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of a non-alternatingalphamethylstyrene:maleic anhydride copolymer of approximate molecularweight 30,000-40,000 prepared using a 50% molar excess of maleicanhydride. Results are shown in TABLE 1.

EXAMPLE 5

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of analphamethylstyrene:maleic anhydride:methacrylic acid terpolymer ofapproximate molecular weight 30,000-40,000, prepared using 20 molepercent methacrylic acid. Results are shown in TABLE 1.

EXAMPLE 6

A WG formnulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of analphamethylstyrene:maleic anhydride:methacrylic acid terpolymer ofapproximate molecular weight 30,000-40,000, prepared using 10 molepercent methacrylic acid. Results are shown in TABLE 1.

EXAMPLE 7

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of analphamethylstyrene:maleic anhydride:methacrylic acid terpolymer ofapproximate molecular weight 30,000-40,000, prepared using 2 molepercent methacrylic acid. Results are shown in TABLE 1.

EXAMPLE 8

A WG formulation was prepared and tested as described in Example 1 withthe dispersant used being the sodium salt of a copolymer ofalphamethylstyrene and maleic anhydride of approximate molecular weight30,000-40,000, prepared by a combination of sodium carbonate and freeacid of the parent polymer. Results are shown in TABLE 1.

EXAMPLE 9

A WG formulation was prepared and tested as described in Example 1 withthe dispersant being a monoammonium salt of an alternating copolymer ofalphamethylstyrene and maleic anhydride. Results are shown in TABLE 1.

EXAMPLE 10

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w MORWET EFW 1.5 (Witco Corp)DISPERSANT 6.2 Water 0.5%

The dispersant used was an alkylnaphthalene formaldehyde condensatesalt, SCS 2258 (ICI Surfactants). The granules were prepared in themanner described in Example 1. The results are shown in TABLE 1.

EXAMPLE 11

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 6.2 Water 0.5%

The dispersant used was a sodium salt of an alternating copolymer ofalphamethylstyrene and maleic anhydride of approximate molecular weight30,000 to 40,000. The granules were prepared and tested in the mannerdescribed in Example 1. The results are shown in TABLE 1.

EXAMPLE 12

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 3.1 Kaolin 3.1 Water 0.5%

The dispersant used was the sodium salt of a 1:1 (mole ratio) copolymerof styrene and maleic anhydride. The granules were prepared and testedin the manner described in Example 1. Results are shown in TABLE 1.

EXAMPLE 13

A Simazine 900 g/kg WG formulation was prepared and tested in the mannerdescribed in Example 6 with the dispersant being the sodium salt of acopolymer of n-octene and maleic anhydride of approximate molecularweight 10,000 to 20,000. Results are shown in TABLE 1.

EXAMPLE 14

A Simazine 900 g/kg WG formulation was prepared and tested in the mannerdescribed in Example 6 with the dispersant being the sodium salt of acopolymer of n-decene and maleic anhydride of approximate molecularweight 10,000 to 15,000. Results are shown in TABLE 1.

EXAMPLE 15

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT <6.2 Kaolin >0 Water 0.5

where the dispersant used was the sodium salt an alternating copolymerof alphamethyl styrene and maleic anhydride of approximate molecularweight 30,000 to 40,000, used at 3.72% w/w and kaolin was used at 2.48%w/w (ie 60% of normal use rate). The granules were prepared and testedin the manner described in Example 1. Results are shown in TABLE 1.

EXAMPLE 16

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of an alternating copolymerof alphamethylstyrene and maleic anhydride used at 3.41% w/w and kaolinwas used at 2.79% w/w. Results are shown in TABLE 1.

EXAMPLE 17

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride of approximate molecular weight30,000 to 40,000, used at 6.2% w/w and kaolin was used at 0% w/w.Results are shown in TABLE 1.

EXAMPLE 18

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride used at 5.27% w/w and kaolin was usedat 0.93% w/w. Results are shown in TABLE 1.

EXAMPLE 19

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride used at 4.34% w/w and kaolin was usedat 1.86% w/w. Results are shown in TABLE 2.

EXAMPLE 20

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride used at 4.03% w/w and kaolin was usedat 2.17% w/w. Results are shown in TABLE 2.

EXAMPLE 21

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride used at 3.72% w/w and kaolin was usedat 2.48% w/w. Results are shown in TABLE 2. These granules still showgood suspensibility.

EXAMPLE 22

A simazine 900 g/Kg WG formulation was prepared and tested as in Example15 where the dispersant was the sodium salt of a copolymer ofdiisobutylene and maleic anhydride used at 3.41% w/w and kaolin was usedat 2.79% w/w. Results are shown in TABLE 2.

EXAMPLE 23

A Simazine 900 g/kg WP formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 3.1 Kaolin 3.4

where the dispersant used was the sodium salt an alternating copolymerof alphamethyl styrene and maleic anhydride. Results are shown in TABLE2. The wettability of the WP was also measured according to CIPAC testMT 53.5.1 and found to be 61 seconds.

EXAMPLE 24

An Atrazine 900 g/kg WG formulation of the following composition wasprepared.

Atrazine tech. (98% w/w) 91.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 3.1 Kaolin 3.1 Water 0.5

where the dispersant used was the sodium salt of an alternatingcopolymer of alphamethylstyrene and maleic anhydride. The granules weremade and tested as described in example 1. Results are shown in TABLE 3.

EXAMPLE 25

A Diuron 900 g/kg WG formulation of the following composition wasprepared.

Diuron tech. (97% w/w) 92.8% w/w ATPLUS G73050 1.5 (now sold under theTrade Mark TERWET 7050, Huntsman Corporation Australia Pty Ltd)DISPERSANT 5.2 Water 0.5

where the dispersant used was the sodium salt of an alternatingcopolymer of alphamethylstyrene and maleic anhydride. The granules weremade and tested as described in example 1. Results are shown in TABLE 3.

EXAMPLE 26

A Simazine 900 g/kg WG formulation of the following composition wasprepared.

Simazine tech. (98% w/w) 91.8% w/w WETTER 1.5 DISPERSANT 6.2 Water 0.5

where the dispersant used was the sodium salt an alternating copolymerof alphamethyl styrene and maleic anhydride used at 6.2% w/w, thewetting agent was the sodium salt dicyclohexylsulphosuccinate used at1.5% w/w and kaolin was used at 0% w/w. The granules were prepared inthe manner described in example 1. Results are shown in TABLE 4.

EXAMPLE 27

A Simazine 900 g/Kg WG formulation was prepared and tested as describedin Example 26 excepting that the wetting agent used was the sodium saltof monocyclohexylsulphosuccinate used at 1.5% w/w. The granules wereprepared in the manner described in example 1. Results are shown inTABLE 4.

EXAMPLE 28

A Simazine 900 g/Kg WG formulation was prepared and tested as describedin Example 26 excepting that the wetting agent used was ECOTERIC AS 20(Huntsman Corporation Australia Pty Ltd), an alkylpolysaccharide used at1.5% w/w on active strength. (The product comes as a 50% solution inwater.) The results are shown in TABLE 4.

EXAMPLE 29

A Simazine 900 g/Kg WG formulation was prepared and tested as describedin Example 26 excepting that the wetting agent used was TERIC 157(Huntsman Corporation Australia Pty Ltd) a nonionic wetter loaded ontoan insoluble porous carrier used at 1.5% w/w. The results are shown inTABLE 4.

EXAMPLE 30

A Simazine 900 g/Kg WG formulation was prepared and tested as describedin Example 26 excepting that the wetting agent used was MORWET EFW(Witco Corp) a sulphonated aromatic based wetter at 1.5% w/w. Theresults shown in TABLE 1.

EXAMPLE 31

An Atrazine 900 g/Kg SC formulation of the following composition wasprepared.

Atrazine tech. 97% w/w 51.5% w/v Monoethylene glycol 4.0 ATLOX 4896A 3(now sold under the Trade Mark TERSPERSE 4896, Huntsman CorporationAustralia Pty Ltd) DISPERSANT 2 Silicone antifoam 0.2 Rhodopol 23 0.2Proxel GXL 20 0.1 Water. 55.0

The dispersant used was the sodium salt of an alternating copolymer ofalpha methyistyrene and maleic anhydride. The SC was prepared bydissolving the monoethylene glycol, ATLOX 4896A (now sold under theTrade Mark TERSPERSE 4896, Huntsman Corporation Australia Pty Ltd) andDISPERSANT in 85% of the water and adding the Atrazine tech. andantifoam with vigorous mixing to form a slurry or millbase premix. Thepremix is then milled using a Dynomill laboratory scale bead mill togive a suitable particle size distribution of >98% of particles below 5μm. The millbase thus obtained was then blended with Proxel GXL 20(Zeneca plc) and Rodopol 23 (Rhodia Inc.) in a premix and then made upto the desired volume with the remaining water and mixed to ahomogeneous mixture. The SC thus obtained was of usable viscosity andwas found to be storage stable after storage at 2 degrees celsius and 50degrees celsius for one month, with minimal syneresis and thickening andno claying, sedimentation or aggregates being observed.

EXAMPLE 32

It was attempted to make an SC formulation according to the formula ofexample 31 with 4% w/w of the sodium salt of an alternating copolymer ofalphamethyl styrene and maleic anhydride and only 1% w/w ATLOX 4896A(now sold under the Trade Mark TERSPERSE 4896, Huntsman CorporationAustralia Pty Ltd) being used. the resulting millbase premix was of aviscosity which would not allow it to be milled

TABLE 1 DISPERSIBILITY SUSPENSIBILITY WET SIEVE RETENTION % EXAMPLE(seconds) (%) 150 μm 53 μm NO. T₀ T₁ T₃ T₀ T₁ T₃ T₀ T₁ T₃ T₀ T₁ T₃ 1 7870 72 83 86 86 0.02 0.01 0.01 0.08 0.09 0.096 2 40 56 3.01 2.49 3 >12077 3 1.7 4 >180 40 14 8.5 5 50 59 85 84 0.006 0.01 0.12 0.08 6 43 56 8180 0.02 0.56 0.2 1.11 7 37 48 81 71 0.01 1.81 0.38 2.64 8 35 59 85 860.007 0.02 0.07 0.14 9 81 130  83 85 0.005 0.002 0.05 0.01 10  52 34 8263 0.017 0.055 0.041 0.89 11  68 56 89 88 0.015 0.025 0.15 0.09 12  5531 0.027 0.095 13  36 39 14  33 59 0.002 0.042 15  85 75 70 83 86 850.02 0.01 0.014 0.09 0.08 0.091 16  74 67 70 85 84 86 0.01 0.015 0.010.04 0.15 0.23 17  69 65 60 86 85 85 0.04 0.026 0.022 0.2 0.16 0.19 30 50 41 42 84 68 60 0.015 0.081 0.62 0.033 4.1 4.2 * T₀ initial results T₁after 1 month storage at 50° C. T₃ after 3 months storage at 50° C.

TABLE 2 WET SIEVE EXAMPLE DISPERSIBILITY SUSPENSI- RETENTION NO.(seconds) BILITY (%) 150 lm 53 lm 18 58 87 0.02 0.23 19 62 86 0.02 0.2120 51 83 0.042 0.19 21 56 82 0.02 0.18 22 60 72 0.02 0.15 23 86 0.020.1 * T₀ initial results only

TABLE 3 WET SIEVE EXAMPLE DISPERSIBILITY SUSPENSI- RETENTION NO.(seconds) BILITY (%) 150 lm 53 lm 24 30 88 0.09 0.6 25 40 79 0.0120.26 * T₀ initial results only

TABLE 4 WET SIEVE RETENTION (%) EXAMPLE DISPERSIBILITY SUSPENSIBILITY150 lm 53 lm NO. WETTING AGENT T₀ T₁ T₀ T₁ T₀ T₁ T₀ T₁ 26dicylohexylsulphosuccinate sodium salt 68 56 88 87 0.065 0.025 0.150.089 27 monocyclohexyl sulphosuccinate sodium salt 70 * 78 * 0.014 *0.09 * 28 Ecoteric AS20 60 61 85 84 0.029 0.025 0.075 0.08 29 TERIC 15761 63 86 86 0.041 0.02 0.2 0.24 * T₀ initial results T₁ after 1 monthstorage at 50° C.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications which fall within itsspirit and scope. The invention also includes all of the steps,features, compositions and compounds referred to or indicated in thisspecification, individually or collectively, and any and allcombinations of any two or more of said steps or features.

What is claimed is:
 1. A method of dispersing an insoluble material inan aqueous solution comprising the following steps: (i) providing aformulation comprising at least one insoluble material and at least onedispersant comprising a water soluble agriculturally acceptablederivative of an alternating copolymer or an agriculturally acceptablesalt thereof wherein said alternating copolymer comprises at least onefirst comonomer residue according to formula I and at least one secondcomonomer residue according to formula II; and

(ii) dispersing said formulation in an aqueous medium.
 2. A methodaccording to claim 1 wherein the alternating copolymer has analternating character defined by greater than 70% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer.
 3. A method according to claim 1wherein the alternating copolymer has an alternating character definedby greater than 90% of consecutive comonomer residue units beingalternate between residues of the first comonomer and the secondcomonomer.
 4. A method according to claim 1 wherein the alternatingcopolymer contains additional comonomer residues which will notsubstantially change the alternating character of the copolymer.
 5. Anagricultural formulation comprising at least one insoluble material andat least one dispersant comprising a water soluble agriculturallyacceptable derivative of an alternating copolymer or an agriculturallyacceptable salt thereof wherein said alternating copolymer comprises atleast one first comonomer residue according to formula I and at leastone second comonomer residue according to formula II.


6. An agricultural formulation according to claim 5 wherein theformulation is in the form of a suspension concentrate (SC), a wettablepowder (WP) or a water dispersible granule (WG).
 7. An agriculturalformulation according to claim 5 wherein the alternating copolymer hasan alternating character defined by greater than 70% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer.
 8. An agricultural formulationaccording to claim 5 wherein the alternating copolymer has analternating character defined by greater than 90% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer.
 9. An agricultural formulationaccording to claim 5 wherein the alternating copolymer containsadditional comonomer residues which will not substantially change thealternating character of the copolymer.
 10. An agricultural formulationaccording to claim 5 wherein the dispersant is an agriculturallyacceptable salt of the alternating copolymer and wherein the saltcomprises sodium, potassium and/or ammonium ions.
 11. An agriculturalformulation according to claim 5 wherein the alternating copolymer is inthe form of its free acid.
 12. An agricultural formulation according toclaim 11 further including a cation source.
 13. An agriculturalformulation according to claim 12 wherein the free acid form of thealternating copolymer and the cation source are capable of reacting togenerate a gas.
 14. An agricultural formulation according to claim 5wherein the dispersant is a water-soluble agriculturally acceptablederivative of the alternating copolymer wherein said derivative isselected from the group consisting of polyethyleneoxy derivatives,polyethyleneglycol derivatives, polyamide derivatives and polyvinylalcohol derivatives.
 15. An agricultural formulation according to claim5 wherein alternating copolymers are in the range of from 1000 to 90000daltons.
 16. An agricultural formulation according to claim 5 whereinthe water-insoluble materials are selected from the group consisting ofherbicides, insecticides, fungicides, biocides, molluscicides,algaicides, plant growth regulators, anthelmintics, rodenticides,nematocides, acaricides, amoebicides, protozoacides, fertilizers, cropsafeners, fillers and carriers and other adjuvants.
 17. An agriculturalformulation according to claim 5 wherein the formulation furthercomprises a surfactant wetting agent.
 18. An agricultural formulationaccording to claim 17 wherein the surfactant wetting agent is selectedfrom the group consisting of an alkylpolysaccharide; di or mono alkylsulphosuccinate derivative; a nonionic surfactant loaded onto an inertsilicate carrier; and a non-ionic surfactant delivered in the form of aurea surfactant complex.
 19. A method of making an agrochemicalformulation comprising the steps of: (i) combining at least oneinsoluble material, and at least one dispersant comprising a watersoluble agriculturally acceptable derivative of an alternating copolymeror an agriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII in an aqueous medium;


20. A method according to claim 19 comprising the steps of: (i)combining at least one insoluble material, and at least one dispersantcomprising a water soluble agriculturally acceptable derivative of analternating copolymer or an agriculturally acceptable salt thereofwherein said alternating copolymer comprises at least one firstcomonomer residue according to formula I and at least one secondcomonomer residue according to formula II in an aqueous medium;

(ii) milling said combination to a particle size range in order toobtain a stable, readily-suspendible aqueous dispersion; and (iii)stabilising said aqueous dispersion to obtain an SC formulation suitablefor dilution in water for agricultural use.
 21. A method according toclaim 19 comprising the steps of: (i) combining at least one insolublematerial, with at least one dispersant comprising a water solubleagriculturally acceptable derivative of an alternating copolymer or anagriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII; and

(ii) milling said combination to a desired particle size to obtain ahomogeneous wettable powder (WP) formulation.
 22. A method according toclaim 19 comprising the steps of: (i) combining at least one insolublematerial suitable for agricultural use with at least one dispersantcomprising a water soluble agriculturally acceptable derivative of analternating copolymer or an agriculturally acceptable salt thereofwherein said alternating copolymer comprises at least one firstcomonomer residue according to formula I and at least one secondcomonomer residue according to formula II; and

(ii) blending said combination to obtain a homogeneous wettable powder(WP) formulation.
 23. A method according to claim 19 comprising thesteps of: (i) combining at least one insoluble material suitable foragricultural use with at least one dispersant comprising a water solubleagriculturally acceptable derivative of an alternating copolymer or anagriculturally acceptable salt thereof wherein said alternatingcopolymer comprises at least one first comonomer residue according toformula I and at least one second comonomer residue according to formulaII;

(ii) agglomerating said combination to form discrete granular materials;and (iii) drying said granular materials to obtain a water dispersiblegranule WG formulation.
 24. A method according to claim 19 wherein thealternating copolymer has an alternating character defined by greaterthan 70% of consecutive comonomer residue units being alternate betweenresidues of the first comonomer and the second comonomer.
 25. A methodaccording to claim 19 wherein the alternating copolymer has analternating character defined by greater than 90% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer.
 26. A method according to claim 19wherein alternating copolymer contains additional comonomer residueswhich will not substantially change the alternating character of thecopolymer.
 27. A method according to claim 19 wherein the dispersant isan agriculturally acceptable salt of the alternating copolymer andwherein the salt comprises sodium, potassium and/or ammonium ions.
 28. Amethod according to claim 19 wherein the alternating copolymer is in theform of its free acid.
 29. A method according to claim 28 furtherincluding the step of incorporating a cation source.
 30. A methodaccording to claim 29 wherein the free acid form of the alternatingcopolymer and the cation source are capable of reacting to generate agas.
 31. A method according to claim 19 wherein the dispersant is awater-soluble agriculturally acceptable derivative of the alternatingcopolymer wherein said derivative is selected from the group consistingof polyethyleneoxy derivatives, polyethyleneglycol derivatives,polyamide derivatives and polyvinyl alcohol derivatives.
 32. A methodaccording to claim 19 wherein alternating copolymers are in the range offrom 1000 to 90000 daltons.
 33. A method according to claim 19 whereinthe water-insoluble materials are selected from the group consisting ofherbicides, insecticides, fungicides, biocides, molluscicides,algaicides, plant growth regulators, anthelmintics, rodenticides,nematocides, acaricides, amoebicides, protozoacides, fertilizers, cropsafeners, fillers and carriers and other adjuvants.
 34. A methodaccording to claim 19 wherein the formulation further comprises asurfactant wetting agent.
 35. A method according to claim 34 wherein thesurfactant wetting agent is selected from the group consisting of analkylpolysaccharide; di or mono alkyl sulphosuccinate derivative; anonionic surfactant loaded onto an inert silicate carrier; and anon-ionic surfactant delivered in the form of a urea surfactant complex.36. A method according to any one of claims 21 to 23 wherein saiddispersant achieves a percentage suspensibility of greater than 80%. 37.A method according to claim 20 wherein said dispersant achieves apercentage suspensibility of greater than 90%.
 38. A method according toeither claim 21 or claim 22 wherein the milling step produces an averageparticle size in the range of from 5 to 15 μm.
 39. A method according toclaim 38 wherein the wettable powder has a wettability of less than 1minute and a suspensibility above 80%.
 40. A method according to claim23 wherein the milling step produces an average particle size in therange of from 5 to 15 μm.
 41. A method according to claim 23 wherein theformulation has a dispersion time of less than 1 minute.
 42. A methodaccording to claim 23 wherein the formulation has a dispersion time ofless than 20 seconds.
 43. A method according to claim 23 wherein theformulation has a wet sieve retention for a 150 μm sieve of less than0.1% retained material and for a 53 μm sieve of less than 0.6%.
 44. Amethod according to claim 23 wherein the milling step produces a meanparticle size of less than 5 μm.
 45. A method according to claim 23wherein the milling step produces a mean particle size in the range offrom 1 to 3 μm.
 46. A method of treatment of a substrate with aninsoluble material comprising the following steps: (i) preparing aformulation comprising at least one insoluble material and at least onedispersant comprising a water soluble agriculturally acceptablederivative of an alternating copolymer or an agriculturally acceptablesalt thereof wherein said alternating copolymer comprises at least onefirst comonomer residue according to formula I and at least one secondcomonomer residue according to formula II;

(ii) dispersing said formulation in an aqueous medium; and (iii)applying the dispersed formulation to a substrate.
 47. A methodaccording to claim 46 wherein the alternating copolymer has analternating character defined by greater than 70% of consecutivecomonomer residue units being alternate between residues of the firstcomonomer and the second comonomer.
 48. A method according to claim 46wherein the alternating copolymer has an alternating character definedby greater than 90% of consecutive comonomer residue units beingalternate between residues of the first comonomer and the secondcomonomer.
 49. A method according to claim 46 wherein alternatingcopolymer contains additional comonomer residues which will notsubstantially change the alternating character of the copolymer.
 50. Amethod according to claim 46 wherein the dispersant is an agriculturallyacceptable salt of the alternating copolymer and wherein the saltcomprises sodium, potassium and/or ammonium ions.
 51. A method accordingto claim 46 wherein the alternating copolymer is in the form of its freeacid.
 52. A method according to claim 46 wherein the dispersant is awater-soluble agriculturally acceptable derivative of the alternatingcopolymer wherein said derivative is selected from the group consistingof polyethyleneoxy derivatives, polyethyleneglycol derivatives,polyamide derivatives and polyvinyl alcohol derivatives.
 53. A methodaccording to claim 46 wherein the water-insoluble materials are selectedfrom the group consisting of herbicides, insecticides, fungicides,biocides, molluscicides, algaicides, plant growth regulators,anthelmintics, rodenticides, nematocides, acaricides, amoebicides,protozoacides, fertilizers, crop safeners, fillers and carriers andother adjuvants.